Companies do trade stocks of other Companies. I guess Roche wanted to make extra $bucks$ buying/selling stocks. Nothing to do with what ARWR drug research. ARWR don't have anything on late staged development.
Why do we think Roche is active in ARWR stock at all? Was there a disclosure? A company like Roche would only deal with ARWR stock for strategic reasons..they don't make their money day trading. IF they were trading the stock they would either be building up a position or divesting an already held position. Do we have any facts about this, or is this all just speculation?